diff --git a/features/FEATURE_BLE/ble/BLETypes.h b/features/FEATURE_BLE/ble/BLETypes.h
index 4c5732dc05..856f3ca84d 100644
--- a/features/FEATURE_BLE/ble/BLETypes.h
+++ b/features/FEATURE_BLE/ble/BLETypes.h
@@ -227,7 +227,7 @@ public:
         for (int i = 5, m = 100000; i >= 0; --i, m /= 10) {
             uint32_t result = passkey / m;
             ascii[i] = NUMBER_OFFSET + result;
-            passkey -= result;
+            passkey -= result * m;
         }
     }